A well-received trading update from Sage Group and strong gains in the mining sector lifted the FTSE 100 into positive territory on Tuesday morning, with sentiment lifted by reassuring comments about Chinese economic growth.

Chinese Premier Li Keqiang is reported to have stood by the government target for economic growth of 7.5% in 2013 and assured that the pace of expansion would not fall below 7.0%: "this bottom line must not be crossed". He called for the government to allow China to grow within a "reasonable range", keeping activity above a "lower limit" and inflation below the "upper limit".

Meanwhile, Vice Premier Zhang Gaoli has said that the ruling party would continue to support infrastructure and social welfare investments.

"This suggests that the ruling party is preparing to announce a new package of stimulus measures which should prevent a hard landing in China in the coming years," said Market Analyst Craig Erlam from Alpari.

"While additional stimulus measures may not be ideal for China’s long-term health, it’s clearly seen as a positive thing now," Erlam said.

Disappointing figures from the US yesterday, where existing-home sales unexpectedly fell in June, also spurred speculation that the Federal Reserve would not rush to withdraw its stimulus measures.

FTSE 100: Sage and miners in demand; Tullow drops

Sage Group said it is confident of delivering its targets as trading in the third quarter was in line with expectations, giving shares a small lift early on.

Oil giant Tullow was a heavy faller this morning after the company said it had plugged and abandoned an exploration well in Mozambique and another in French Guiana.

Budget airline easyJet was also in the red ahead of its third-quarter trading update due on Wednesday morning; British Airways owner IAG was also lower. The falls come after sector peer Ryanair announced its decision to sell its 29% stake in Irish airline Aer Lingus to another EU airline.

Speciality chemicals firm Croda fell after its interim results, in which it reported a 6.3% year-on-year rise in pre-tax profit and an 8.4% increase in the dividend. The company admitted that the "challenging trading environment has inevitable held back certain parts of the business".

Investors welcomed the approval by Chinese authorities for Diageo to buy up the remaining 47% stake in SJF HoldCo for £233m. The investment lifts the company's indirect holding in Chinese premium spirits maker Sichuan Shuijingfang.